1. Field
The present invention relates to an information recording device and an information recording method for recording information on a recording medium.
2. Description of the Related Art
In recent years, various techniques have been developed to increase the recording capacity of a magnetic disk device (hereinafter also referred to as HDD) which is an information recording device. Among these techniques is a recording technique called “shingled write recording method.” The shingled write recording method is a recording method in which information is recorded on a magnetic disk in such a manner that a recording track is superimposed on part of an adjacent track. The shingled write recording method makes it possible to increase the TPI (tracks per inch).
In the shingled write recording method, a track group (hereinafter also referred to as “band”) consisting of plural adjacent tracks is defined as a unit of recording. At least one band capable of storing information is secured as a spare band. To update (rewrite) the information recorded on a certain band, update subject information is rewritten to a spare band rather than the band from which original information has been read. The band in which the original information has been recorded is used as a new spare band. In this manner, in the shingled write recording method, the spare band moves from one position to another.
In HDDs, a problematic phenomenon called ATI (adjacent track interference) that magnetic interference from a recording track affects the holding of information of a track adjacent to it may occur. Stored information may be destroyed by ATI. The ATI problem becomes more serious as TPI increases in the shingled write recording method, for example. The ATI problem is avoided by updating (rewriting) the information stored in each of tracks that appear vulnerable to API before it is affected. For example, if the number of times of recording on a track adjacent to a certain track has exceeded a prescribed number, the information recorded on the certain track is updated.